Method for operating a heat exchanger, arrangement with a heat exchanger, and system with a corresponding arrangement

The invention relates to a method for operating a heat exchanger (1), in which a first operating mode is carried out in first time periods, and a second operating mode is carried out in second time periods that alternate with the first time periods; in the first operating mode a first fluid flow (A) is formed at a first temperature, is fed into the heat exchanger (1) in a first region (2) at the first temperature, and is partially or completely cooled in the heat exchanger (1); in the first operating mode a second fluid flow (B) is formed at a second temperature, is fed into the heat exchanger (1) in a second region (3) at the second temperature, and is partially or completely heated in the heat exchanger (1); and in the second operating mode the feeding of the first fluid flow (A) and of the second fluid flow (B) into the heat exchanger (1) is partially or completely halted. Either in the second time period, or in a third time period which lies between at least one of the second time periods and the subsequent first time period, heat is supplied to the first region (2), the heat being provided by means of a heating device (7) arranged outside the heat exchanger (1), and the heat being transferred to the first region (2) via a gas chamber (5) located outside the heat exchanger (1). A corresponding arrangement (10) and a system (100, 200) with such an arrangement (10) are also covered by the present invention.